Let's face it, guys -- anything that has moving parts can fail. And a bunch of stuff without moving parts can fail, too.

There is a difference between equipment that fails because it's poorly designed and equipment that fails because it's poorly made or just because things happen that you can't prevent and wouldn't be expected to foresee.

It's not, I don't think, that anyone thinks that any given organization is incompetent at making any given piece of equipment. I think Steve is right, we tend to get more nervous about devices with more moving parts than we do about devices with less moving parts (witness the greater worries about Sterling RTGs and their moving pistons vs. the more classic thermocouple-based RTGs with no moving parts).

It is important to remember that almost all moving parts on almost every spacecraft we've ever launched have worked perfectly. My feel for it is that more spacecraft have died because of electronics failures than have died because a moving part broke or stuck. But we seem to remember and worry about the moving part failures more than about fried electronics...

-the other Doug

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“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain

One last (?) word on the Mastcam mechanisms. A mechanismless system would be more reliable, certainly. But it would also have compromised performance. We looked at fixed-focus systems like Pancam and concluded that the performance hit was too great (Pancam is really slow optically and it's only in best focus at 2m target distance.) Our mechanisms are as reliable as we know how to make them and make as much use of MER heritage as possible. We tested them for 3x mission life and they passed with no issues. If people have residual reliability concerns, I'd be curious to know how they think we could address them. But you'd probably have to know more details of the mechanisms than is publicly available to have a well-founded opinion.

If our cameras fail there will be plenty of B&W Navcam images.

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Disclaimer: This post is based on public information only. Any opinions are my own.

Did you trust the MER Pancam filter wheel or the MI cover to not lock up?...

As a matter of fact, I have had doubts about that as well My perspective is reflective of my experience with commercial digital cameras -- true, the engineering quality isn't the same, but it's also true that every actuator-driven motion is a potential failure point, and I worry about that abrasive wind-blown dust. I'd lean towards solid-state systems, perhaps an optical phased array

Seem to have touched a bit of a nerve here. I'm afraid that I am indeed guilty of playing armchair engineer -- and I've had a lot of fun doing it

"In retrospect they might simply have placed a dedicated third camera with fixed telephoto capability centered between a pair of stereo wide angle cams on the mast head with rather less trouble and similar capabilities as the dual zoom system."

There are no unused MSSS camera interfaces in the MSL rover. If you want to lobby for an additional camera mention there are three unused engineering camera interfaces.

One question about the RTG in MSL: in front of the natural decay of plutonium, will be the amount of power available for MSL lesser with the two years delay of launch?

It was previously discussed. The answer was that the loss of power is not of concern since it is very small. About how much, I don't remember but the reference is to take in account that the half life span of this type of radiative is of 88 years.Wikipedia about Plutonium

My favorite solution is to mount the panels on vertical surfaces, like the sides of the electronics box. They would give less power with the sun overhead, but more with the sun near the horizon. Best of all, they should stay clean with no additional cleaning apparatus needed.

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